4-Alkoxy nucleosides and intermediates therefore

ABSTRACT

Novel 4&#39;&#39;-Alkoxy- Beta -D-ribofuranosyl, 4&#39;&#39;-alkoxy-2&#39;&#39;-deoxyBeta -D-erythro-pentofuranosyl and 4&#39;&#39;-alkoxy- Beta -Darabinofuranoxyl nucleosides and the corresponding 4&#39;&#39;-haloalkoxy nucleosides can be prepared from the respective 4&#39;&#39;-alkoxy-5&#39;&#39;deoxy-5&#39;&#39;-iodo- Beta -D-ribofuranosyl, 4&#39;&#39;-alkoxy-2&#39;&#39;, 5&#39;&#39;-dideoxy5&#39;&#39;-iodo- Beta -D-erythropentofuranosyl and 4&#39;&#39;-alkoxy-5&#39;&#39;-deoxy5&#39;&#39;-iodo- Beta -D-arabinofuranosyl nucleosides. The novel 4&#39;&#39;-alkoxy and 4&#39;&#39;-haloalkoxy nucleosides are valuable pharmacological agents. For example, they are useful in regulating and controlling metabolism and for producting metabolic deficiencies in biological systems.

United States Patent [191 Moffatt et al.

[ 1 Oct. 7, 1975 1 1 4-ALKOXY NUCLEOSIDES AND INTERMEDIATES THEREFORE [75] Inventors: John G. Moffatt; .lulien P. H.

Verheyden, both of Los Altos, Calif.

[52] US. Cl 260/2115 R; 424/180 [51] Int. Cl. CO7H 19/06; CO7H 19/00 [58] Field of Search 260/2115 R [56] References Cited UNITED STATES PATENTS 6/1971 Verheyden et al 260/2115 R 6/1974 Jenkins et a1. 260/2115 R Primary Examiner-Johnnie R, Brown Attorney, Agent, or FirmGerard A. Blaufarb; William E. Walker [57] ABSTRACT Novel 4'-Alkoxy-B-D-ribofuranosyl, 4'alk0xy-2 deoxy-B-D-erythro-pentofuranosyl and 4'-alkoxy-B-D- arabinofuranoxyl nucleosides and the corresponding 4-hal0alk0xy nucleosides can be prepared from the respective 4' a1k0xy-5 -deoxy-5 -iodoB-D- ribofuranosyl, 4-alkoxy-2', 5'-clideoxy-5-iodo-B-D- erythropentofuranosyl and 4 a|koxy-5'-de0xy-5- iodo-B-D-arabinofuranosyl nucleosides.

The novel 4-alkoxy and 4-haloalkoxy nucleosides are valuable pharmacological agents. For example, they are useful in regulating and controlling metabolism and for producting metabolic deficiencies in biological systems.

20 Claims, No Drawings 4-ALKOXY NucLEosmEs AND INTERMEDIATES a THEREFORE SUMMARY R The novel 4'-alkoxy and the corresponding 4'- 5 R0 haloalkoxy nucleosides of this invention can be represented by the formula: (III C) wherein R and R are as previously defined and B is a hydrolyzable acyl derivative of a pyrimidine or purine base;

with lithium benzoate in an inert organic solvent (1) under reactive conditions at temperatures in the range of 80 to 140C. to obtain the corresponding wherein: 5'-benzoyloxy compound; and

B is a pyrimidine or purine base or a hydrolyzable b. treating said 5'-benzoyloxy compound with a base acyl derivative thereof derived from a carboxylic 2O SEleCted from Concentrated aflimCmlum hydroxlde acid having I to l2 carbons; in methanol (1:1) or methanohc ammonia at tem- R is methyl, ethyl, CH CH X, CH CHX or peratures in the range of to 100C. until there CH CX and each X is Cl or F; is formed the corresponding compound of Formula one of R and R is hydrogen and the other is hydro- 1 gen or OR"; and

each of R, R and R are hydrogen or a hydrolyzable acyl group having I to l2 carbons; provided that when both R and R are hydrogen, B is a pyrimidine base.

The S'-iodo nucleoside intermediates of this invention can be represented by the formulas:

I B I B 8 R L0 wherein R is as previously defined; B is a pyrimidine or R0 R0 purine base; and OR", OR and one of R and R are hydrox OH 7 ,11 9 y The compounds of the present invention are useful in (III) regulating and controlling metabolism and for producing metabolic deficiencies in numerous biological systerns or are intermediates for such compounds. The wherem compounds further exhibit antibacterial and antiviral B and R l as EW E W dcscrabedih h d activity, central nervous system activity and cardiac one of R and R IS ydrogen, t e ot er 1 y rogen and circulatory activity and correspondingly are useful or f gg R h d h h h d in the treatment of the corresponding disorders in one 0 H an y Ogen t e er y roger mammals. Moreover, the compounds of the present in- RS 811 "d I b] l h l t 12 vention are analogs of known nucleosides having is a y m yza e acy group avmg 0 Car- 5 known pharmacological properties, for example, 3 atfimsi h R d R R d R both 5-alkyl2 deoxy-uridine is a known antibacterial agent grcciivi ed tBat w en b of are (note: British Pat. No. l,l70,565); 6-halo-9-deaza-8- y roger" a pynm' me azaadenosine and Q-B-D-arabinofuranosyl adenine tri- In yh lk E f: i fs l Pj ester are known active antivirals (note: Japanese Frat. mg novel OXY my e051 es N0. 70/25,!02 and us. Pat. No.3,651,045);N, 0 compns'zisI O O -tetraacylated cytidine is a central nervous treatmg a 5 'lodo'nucleoslde Selected from the system activator (note: German Pat. No. 2,038,807); group represented by the formulas: 2-haloadenosine compounds, particularly 2- fluoroadenoise compounds, are effective in the treat- I B ment of cardiac and circulatory disorders (note: Neth- I erlands Pat. No. 6,717,061); and the cytosine nucleosides, particularly the arabinofuranosyl derivatives, are important as antiviral and antineoplastic agents (note: R0 R0 Japanese Pat. No. 71/38,]56 and U.S. Pat. No.

ll 11 ,5 3,72l,664). R OR oa H The term pyrimidine base as used herein refers to (III-A) (III-B) an unsubstituted or substituted pyrimidine or 6- zene ring or other aromatic ring and containing from 7 to 12 carbon atoms such as benzyl. The term substituted aryl" refers to an aryl group having one or more halo, nitro, alkoxy or dialkylamino substituents in the aromatic ring such as p-chlorobenzyl, p-bromobenzyl, 2,4,6-trifluorophenyl, p-nitrophenyl, p-nitrobenzyl, panisyl, p-methoxybenzyl, p-dimethylaminophenyl, and the like.

DETAILED DISCUSSION The novel nucleosides of this invention represented by Formula I can be prepared in accordance with the following reaction sequence:

1 2 B O I O on R7 R11 R9 (II) (III) S-trifluoromethyluracill -yl, S-nitrouracill-yl, 5- methylaminouracil-l-yl, S-dimethylaminouracil-l-yl, (s-aza-uracill-yl, 6-aza-5-methyluracill -yl, cystosinl-yl, S-fluorocystosin-l-yl, S-alkylcytosin-l-yl, 5- trifluoromethylcytosinl -y1, S-nitrocytosinl -yl, 5- methylaminocytosinl -yl, S-dimethylaminocytosinl-yl, o-uzacytosinl -yl, 6-aza-5-methylcytosinl -yl, adenin-9-yl, 2-fluoroadenin-9-yl, 2-azaadenin-9-yl, 7- deazaadenin-9yl, 8-azaadenin-9-yl, 8-aza-9- deazaadenin-Q-yl, 7-deaza-7-cyanoadenin-9-yl, N- methyladenin-9-yl, N -methyladenin- -yl, N- dimethyladenin-9-yl, guanin-Q-yl, 8-azaguanin-9-yl, 7- deazaguanin-9-yl, isoguanin-9-yl, hypoxanthin-9-yl and xanthin-Q-yl.

The terms hydrolyzable esters,"hydrolyzable acyl derivatives" and hydrolyzablc acyloxy groups" as used herein refer to those esters and acyl derivatives conventionally employed in the nucleoside and nucleotide art, preferably those derived from carboxylic acids of l to 12 carbon atoms. Typical conventional hydrolyzablc acyl groups include acetyl, propionyl, butyryl, valeryl, isovaleryl, hexanoyl, heptanoyl, octanoyl, nonanoyl, undecanoyl, lauroyl, benzoyl, phenylacetyl, phenylpropiony], 0-, m-, p-methylbenzoyl, B-cyclopentylpropionyl, dihydrocinnamyl, and the like.

The term lower alkyl" as used herein, refers to a straight chain hydrocarbon group containing from 1 to 5 carbon atoms inclusive, such as methyl, n-propyl, nbutyl, and the like.

The term aryl, as used herein, refers to a hydrocarhon group consisting of one or more aromatic rings and containing from 6 to 12 carbon atoms, inclusive, such as phenyl, henzyl, o-tolyl, m-tolyl, p-tolyl, 3,5-xylyl, pentamethylphenyl, naphthyl, and the like. The term aralkyl" refers to a hydrocarbon group having a ben- B represents uracil-l-yl, 5-fiuorouracil-l-yl, 5- alkyluracill -yl, S-trifluoromethyluracill -yl, 5- nitrouracill -yl, S-methylaminouracill -yl, 5-

dimethylaminouracill -yl, 6-azauracill -yl, 6-aza- S-methyluracill -yl, N-benzoylcytosinl -yl, N benzoyl-S-fluorocytosinl -yl, N-benzoyl-5- alkylcytosinl-yl N-benzoyl-5-trifluoromethylcytosin-l-yl, N -benzoyl-5-nitrocytosin-l-yl, N- benzoyl-S-methylaminocytosin- 1 -yl N -benzoyl-5- dimethylaminocytosinl -yl, N -benzoyl-6- azacytosinl -yl, N-benzoyl-6-aza-5-methylcytosinl -yl, N ,N-dibenzoyladenin-9-yl N l N- dibenzoyl-2-fluor0adenin-9-yl, N,N-dibenzoyl-7- deazaadenin-9-yl, N',N -dibenzoyl-8-azaadenin- 9-yl, N,N-dibenzoyl-8-aza-9-cleazaadenin-9-yl, N ,N-dibenzoyl7deaza-7-cyanoadenin-9-yl, N benzoyl-N-methyladenin-9-yl, N -climethyladenin- 5 9-yl. N -benzoylguanin-9-yl, N -benzoyl-8- azaguanin-9-yl, N benzoyl-7-deazaguanin-9-yl, N"-benzoyl-isoguanin-Q-yl, hypoxanthin-Ql-yl and Xanthin-Q-yl.

The nucleoside of Formula 11 is treated with an acylating agent, preferably benzoyl chloride, in an inert an hydrous organic solvent such as pyridine at a temperature of to 30C. for a period of 8 to 24 hours to yield the perbenzoylate'd nucleoside of Formula Ill.

The nucleosides of Formula IV are prepared by treating nucleosides of Formula 111 with lithium benzoate in an anhydrous organic solvent such as hexamethylphosphorotriamide at a temperature of 80 to 140C. for at least 12 hours until the -benzoyloxy-perbenzoylated nucleosides of Formula IV are formed.

The nucleosides of Formula IV are treated with a base to yield the unprotected 4'-alkoxy or 4'- hlaoalkoxy nucleosides of Formula 1 wherein OR", OR and one of R and R are hydroxy. Treatment with concentrated ammonium hydroxide in methanol at a temperature betweenand 100C. for from 1 to 24 hours is usually sufficient for removing all acyl protecting groups. The unprotected 4'-alkoxy or 4'-haloalkoxy nucleosides can then be esterified to yield compounds of Formula 1 wherein 0R OR and one of R and R are acyloxy. To form the O-benzoyl or substituted benzoyl esters, the unprotected nucleoside is reacted with benzoyl chloride, or an alkyl, nitro, or chloro substituted benzoyl chloride in a pyridine solution for from 15 minutes to 2 hours at about 0C., following which the reaction is maintained at room temperature for at least 4 hours. The unprotected nucleoside can also be esterified with a lower aliphatic hydrocarbon acyl group such as acetyl, propionyl, butyryl, valeryl, dihydrocinnanyl and the like by reacting the unprotected nucleoside with the corresponding lower aliphatic hydrocarbon acid chloride in pyridine at about room temperature for at least 4 hours. The preferred ester groups are benzoyl or substituted benzoyl.

The 4-alkoxy-5'-deoxy-5-iodo-B-D-ribofuranosyl nucleoside intermediates and the corresponding 4'- haloalkoxy nucleoside intermediates of Formula 11 wherein R is hydroxy and R is hydrogen can be prepared in accordance with the following reaction se quence:

3 no 0 B I k 7 1n the above sequence R and B are as previously defined:

B represents uracil-l-yl, 5fluorouracil-lyl, 5- alkyluracill -yl, S-trifluoromethyluracill -yl, 5- nitrouracill-yl, S-methylaminouracill -yl, 5-

dimethylaminouracill -yl, -azauracill -y1, 6-aza- S-methyluracil- 1 -yl, N -acetylcytosinl -yl, N- acetyl-S-fluorocytosinl -yl N acetyI-S- alkylcytoxinl -yl, N-acctyl-5-trifl uoromethylcytosinl -yl, N -acetyl-5-nitrocytosin- 1 -yl, N acetyl-5-methylaminocytosin- 1 -yl, N-acetyl-5- dimethylaminocytosinl -yl N -acetyl-6- azacytosin,l-yl, N -acetyl-6-aza-5-methyl cytosinazaadenin-Q-yl, N-benzoyl-8-zaz-9-deazaadenin- 9-yl, N-benzoyl-7-deaza-7-cyanoadenin-9-yl, N- benzoyl-N-methyladenin-9-yl, N -dimethyladenin- 9-yl,N -acetylguanin-9-yl,N -acetyl-8-azaguan- 9-yl, N -acetyl-7-deazaguanin-9-yl, N-acetylisoguanin-9-yl, hypoxanthin- 9-yl. and xanthin 9-yl; and

B represents uracil-l-yl, S-fluorouracil-l-yl, 5- alkyluracill -yl, S-trifl uoromethyluracil-l -yl, 5- nitrouracil- 1 -yl, S-methylaminouracill-yl, 5-

aralkyltriaryloxyphosphonium iodide, preferably methyltriaryloxyphosphonium iodide. This halogenation is carried out in an anhydrous inert organic solvent at a temperature between and 30C. for a period of 15 to 120 minutes. Suitable inert organic solvents for the halogenation of pyrimidine nucleosides include dimethylformamide, dimethylacetamide and hexamethylphosphorotriamide, preferably dimethylformamide. The halogenation of purine nucleosides is carried out by suspending the purine compound in a suitable anhydrous solvent, cooling the well stirred suspension to a temperature between 80 and 70C. prior to adding the halogenating agent under anhydrous conditions, and then allowing the reaction mixture to warm to a temperature between 15 and 35C. over a period of 2 to 8 hours. Suitable organic solvents for the halogenation of purine nucleosides include methylene chloride, tetrahydrofuran and dioxane with methylene chloride preferred. The 2',3'-O- isopropylidene protecting groups are then cleaved with an organic acid to yield the corresponding free hydroxy nucleoside compounds of Formula VII.

The nucleosides of Formula VIII are prepared by de hydrohalogenation and subsequent carbonation of nucleosides of Formula VII. The preferred procedure for the preparation of nucleosides of Formula VIII, with the exception of nucleosides wherein B is an unsubstituted or substituted adenin-Q-yl, 2-azaadenin-9-yl, 8- azaadenin-Q-yl, 7-deazaadenin-9-yl or 8-aza-9- deazaadcnin-9-yl, comprises dehydrohalogenating a nucleoside of Formula VII with l ,5- diazabicyclo[4,3.()lnon-S-ene in an anhydrous basic organic solvent such as pyridine or an alkyl substituted pyridine, e.g. picolines, at a temperature between 15 and 25C. for a period of 12 to 48 hours. The resulting reaction mixture is cooled to a temperature between 80 and 70C. A solution of phosgene in benzene is added under anhydrous conditions and the reaction mixture is allowed to warm to a temperature between 15 and 25C. over a period of 1 to 2 hours.

In the preparation of nucleosides of Formula VIII wherein B is an unsubstituted or substituted adenin- 9-yl, 2-azaadenin-9-yl, 8-azaadenin-9-yl, 7- deazaadenin-Q-yl or 8-aza-9-deaxaadcnin-9-yl base, the corresponding nucleoside of Formula VII is first dehydrohalogenated with l ,5-diazabicyclo[4.3.0]non--ene in an anhydrous organic solvent such as dimethylformamide, dimethylacetamide or hexamethylphosphorotriamidc. preferably dimethylformamide. The reaction is carried out in the absence of light at a temperature of 15 to 25C. for a period of 12 to 24 hours. Thereafter the reaction mixture is evaporated to dryness and the residue is purified by chromatography over silica gel in order to remove all N-debcnzoylated material. The thus-obtained pure N-benzoyl-4,5'-unsaturated nucleoside is then dissolved in an anhydrous basic organic solvent, the solution is cooled to a temperature between 8() and 70C. and a solution of phosgene in benzene is added. Suitable basic organic solvents include pyridine and alkyl substituted pyridines such as picolines. The reaction mixture is allowed to warm to a temperature between 15 and 25C. over a period of I to 2 hours and is then evaporated to dryness under vacuum. The resulting residue is purified by partition between chloroform and percent aqueous sodium bicarbonate. The organic layer is washed with water, dried with magnesium sulfate, filtered and evaporated to dryness. The resulting syrupy residue is then dissolved in an anhydrous basic organic solvent, such as pyridine and treated with an acylating agent, preferably benzoyl chloride. The reaction is carried out at a tem perature of to C. for a period of 12 to 24 hours.

This acylation reaction produces the N,N- 5 dibenzoylated 4',5'-unsaturated nucleoside of Formula VIII (wherein B is limited to the previously enumerated bases) and prevents the possibility of N ,4'or N ,5'-cyclization.

The nucleosides of Formula IX are prepared by treating a 4',5-unsaturated nucleoside of Formula V1" with iodine and a lower alkanol or haloalkanol. The reaction is carried out by dissolving a nucleoside of Formula VIII in a lower alkanol or haloalkanol containing a molar excess of silver acetate or lead carbonate and then vigorously stirring while treating with iodine in the absence of light at a temperature of 15 to 25C. for a period of 15 minutes to 2 hours. Alkanols and haloalkanols that can be employed in the process of the present invention include methanol, ethanol, 2- chloroethanol, 2,2-dichloroethanol and 2,2,2- trichloroethanol and the corresponding fluoroalkanols.

The nucleosides of Formula X are prepared by removing all protecting groups in nucleosides of Formula VIII by treatment with a base such as sodium methoxide or barium methoxide in methanol at a temperature between 15 and 25C. for 15 minutes to 1 hour. The reaction mixture is then neutralized by the addition of an ion exchange resin (Amberlite IRC 5O COO'H"). The mixture is filtered, the resin is thoroughly washed with methanol and the combined filtrate and washings then evaporated to dryness. The residue is purified by chromatography over silica gel.

Although not depicted in the reaction sequence, a nucleoside of Formula X can be converted to the a-L- lyxo isomer by dissolving in 0.1 N methanolic I-ICL (other appropriate alcohols may also be used) and following the equilibration which takes 2 to 24 hours by thin-layer chromatography.

The 4'-aIkoxy-2 ,5 dideoxy- 5 iodo-B-D-e rythropentofuranosyl nucleosides of Formula II where R and R" are hydrogen and the 4'-alkoxy-5'-deoxy-5'-iodo-B- D-arabinofuranosyl nucleosides of Formula II where R is hydrogen and R is hydroxy can be prepared in accordance with the following reaction sequence:

1 2 no 5 H s H a L R (XI) (XII) 2 R Ca 15 15 on H OR H (XIVl (XIII) 1 1 El ca 2 on s OH H (XVI) In the above sequence R, B and B are as previously defined;

R is hydrogen or hydroxy;

R is hydrogen or hydrolyzable acyloxy; and

R" is a hydrolyzable acyl group; provided that when R is H, B is a pyrimidine base.

The nucleosides of Formula Xll are prepared by first etherifying the known nucleosides of Formula X] at the 5'-position with monomethoxytrityl chloride in a basic organic solvent such as pyridine or an alkyl substituted pyridine (e.g. picolines) at a temperature between and 25C for a period of 12 to 24 hours. The resulting 5-etherified product without further purification is then treated with an acylating agent, such as benzoyl chloride, in dry pyridine at a temperature between 15 and 25C for a period of 12 to 24 hours to yield the 5'- etherified perbenzoylated nucleoside. The 5'-ether group is then selectively cleaved with an organic acid to yield the nucleoside of Formula Xll. All substituted and unsubstituted B-D-arabinofuranosylcytosine and 6-azacytosine nucleosides of Formula XI wherein R is hydroxy, are converted to the N -benzoyl derivative prior to the above-described etherification. This acylation is carried'out with benzoic anhydride in ethanol at reflux for a period of 6 to 8 hours.

The nucleosides of Formula Xlll are prepared by halogenating the respective nucleoside esters of Formula Xll with an alkyltriaryoxyphosphonium iodide or an aralkyltriaryloxyphosphonium iodide, preferably with methyltriphenoxyphosphonium iodide. The halogenation of 2'-deoxy-and arabinofuranosyl pyrimidine nucleosides is carried out in an inert organic solvent at a temperature of 15 to 25C for a period of IS minutes to 2 hours. Suitable solvents include dimethylformamide, dimethylacetamide or hexamethylphosphorotriamide, dimethylformamide being preferred. The halogenation of arabinofuranosyl purine nucleosides is carried out by suspending the respective nucleoside of Formula XII wherein R is acyloxy, in a suitable solvent, cooling the solution to a temperature between -80 and 70C and adding, under anhydrous conditions and vigorous stirring, methyltriphenoxyphos phonium iodide. The reaction mixture is allowed to warm to a temperature between 15 to 25C over a period of l to 3 hours. Suitable solvents for the halogenation of the purine nucleosides include methylene chloride, tetrahydrofuran and dioxane, with methylene chloride preferred.

The nucleosides of Formula Xlll are dehydrohalogenated by treating with silver fluoride to give the 4',5'-unsaturated nucleosides of Formula XIV. The dehydrohalogenation reaction is run in a basic organic solvent at a temperature between 15 and 25C for a period of 96 to I hours. As a basic organic solvent pyridine or alkyl-substituted pyridines (e.g. picolines) can be used, with pyridine preferred. Alternatively, nu-

cleosides of Formula Xlll can be dehydrohalogenated by treating with 1,5-diazabicyclo[4.3.0]-non-5-ene in an anhydrous organic solvent such as dimethylformamide, dimethylacetamide or hexamethylphosphorotriamide, preferably dimethylformamide, at a temperature of l5 to C for a period of 21 to 48 hours.

The O-benzoyl protecting groups are then cleaved in the nucleosides of Formula XIV to give the free hydroxy nucleosides of Formula XV. This hydrolysis can be carried out with sodium hydroxide in a mixture of ethanol and pyridine at a temperature of 15 to 25C for a period of 5 to 10 minutes.

The nucleosides of. Formula XVl are then prepared by iodoalkoxylation of nucleosides of Formula XV with iodine and a lower alkanol or haloalkanol. The reaction is carried out as previously described for the preparation of 4'-alkoxy5-deoxy-5'-iodo-B-D-ribofuranosyl nucleosides of Formula X. The resulting reaction product is a mixture of isomers, e.g. iodoalkoxylation of a 4',5-unsaturated-2'-deoxy pyrimidine nucleoside yields the B-D-erytho-pentofuranosyl and the a-L- threo-pentofuranosyl isomers, whereas iodoalkoxylation of a 4',5'-unsaturated-arabinofuranosyl nucleoside yields the B-D-arabinofuranosyl and a-L-xylofuranosyl isomers. The isomers are separated by acetylation of the reaction mixture with acetic anhydride followed by physical separation by thin-layer chromatography. The pure isomers are then completely deacylated by treatment with a base such as ammonium hydroxide in methanol or methanolic ammonia at a temperature of 25 to C for a period of l to 24 hours to yield 4'- alkoxy-Z ',5 -dideoxy-5 '-iodo'B-D- erythropentofuranosyl or 4-alkoxy-5'-deosy-5'-iodo- B-D-arabinofuranosyl nucleosides. Examples I through 27 relate to preparation of the 5'-iodo nucleoside intermediates of Formulas II and Ill.

EXAMPLE 1 5 'deoxy-5 '-iodo-uridine 2',3'-O-isopropylidene-uridine l mmole) is dissolved in i0 ml. of dry dimethylformamide and methyltriphenoxyphosphonium iodide (1.2 mmole) is added. After 15 minutes at 20C the excess reagent is decomposed with methanol and the solvents are evaporated under vacuum. The resulting residue is partitioned between ethylacetate and water and the ethylacetate layer is successively washed with an aqueous 10 percent solution of sodium thiosulfate and water. The organic layer is then dried over magnesium sulfate, filtered and evaporated to dryness. The residue is purified by chromatography over silica gel and the desired nucleoside containing fractions are collected and evaporated to dryness under vacuum. The resulting residue is then dissolved in 5 ml. of a mixture of formic acid and water (9:1). After 48 hours at 30C the solvents are evaporated under vacuum. The residue is dissolved in a mixture of methanol and water (1:1) and the pH of the solution is adjusted to 8.5 in order to hydrolyze residual formate groups. The solvents are then evaporated under vacuum and the residue is chromatographed over silica gel. The nucleoside containing fractions are collected and evaporated to dryness. The resulting residue is crystallized from methanol to yield 5 deoxy-S '-iodouridine.

EXAMPLE 2 5 -deoxy-5 -iodo-,B-D-ribofuranosyl pyrimidines Repeating the procedure of Example I but replacing 2',3'-O-isopropylidene-uridine with 2,3-O-isopropylidene-5-fluorouridine, 2,3'-O-isopropylidene-S-butyluridine, 2',3-O-isopropylidene-5-tritluoromethyluridine, 2,3'-O-isopropylidene-S-nitrouridine, 2',3'-O-isopropylidene-S-methylaminouridine, 2',3-O-isopropylidene-S-dimethylarninouridine, 2',3-O-isopropylidene-6-azauridine, 2',3O-isopropylidene-6-aza-5-methyluridine, N-acetyl-2 ',3 -O-isopropylidene-cytidine,

N -acetyl-2 ,3 -O-isopropylidene-S-fluorocytidine, N -acetyl-2',3-O-isopropylidene-S-butylcytidine, N-acetyl-2',3'-O-isopropylidene-S-trifluoromethylcytidine, N-acetyl-2',3-O-isopropylidene-S-nitrocytidine. N-acetyl-2',3-O-isopropylidene-5- methylaminocytidine, N-acetyl-2,3'-O-isopropylidene-5 dimethylaminocytidine, N -acetyl'2',3'-O-isopropylidcne-fi-azacytidine, and N-acetyl-2',3'-O-isopropylidene-6-aza-5- methylcytidine yields the corresponding,

5 '-deoxy-S -iodo-5-fl uorouridine, 5-deoxy-S-iodo-5-butyluridine. 5 '-deoxy-5 -iod-5-trifluoromethyluridine, -deoxy-5'-iodo-5-nitrouridine, 5-deoxy-5'-iodo-5-methylaminouridine, 5'-deoxy-S'-iodo-S-dimethylaminouridine, 5-deoxy-5'-iodo-6-azauridine, Sdeoxy-S'-iodo-6-aza-S-methyluridine, N -acctyl-5 '-deoxy-5 '-iodo-cytidine. N-acetyl-5 -deoxy-5 '-iodo-S-fluorocytidine, N -acetyl-S'-deoxy-5'-iodo-S-butylcytidine, N*-acetyl-5 '-deoxy-5 -iodo-S-trifl uoromethylcytidine, N-acetyl-5 '-deoxy-5 '-iodo-5-nitrocytidine, N-acetyl-5 '-deoxy-5 '-iodo-5-methylaminocytidine, N*-acetyl-5'-deoxy-5'-iodo-5- dimethylaminocytidine, N-acetyl-5'-deoxy-5'-iodo-6-azacytidine, and N-acetyl-6-aza-5-methylcytidine.

EXAMPLE 3 N -bcnzoyl-5 '-deoxy-5 '-iodo-adenosine N -benzoyl-Z 3 '-O-isopropylidene-adenosine (l mmole) is suspended in 10 ml. of dry methylene chloride, and the solution is cooled to70C. Methyltriphenoxyphosphonium iodide (1.5 mmole) is then added in a dry nitrogen atmosphere and the reaction mixture is allowed to warm to C. Two hours after the addition of methyltriphenoxyphosphonium iodide. the excess reagent is decomposed with methanol and the solvents are evaporated under vacuum at 30C. The resulting residue is partioned between chloroform and water, and the chloroform layer is succes sively washed with an aqueous 10 percent solution of sodium thiosulfate and water. The chloroform layer is then dried over magnesium sulfate, filtered and evaporated under vacuum. The resulting residue is dissolved in 10 ml. of a mixture of formic acid and water (9:1). After 48 hours at 30C the solvents are evaporated under vacuum. The residue is dissolved in a mixture of methanol and water (1:1) and the pH of the solution is adjusted to 8.5 in order to hydrolyze residual formate groups. The solvents are then evaporated under vacuum and the residue is purified by chromatography over silica gel. The nucleoside containing fractions are collected and evaporated to dryness to yield N benzoyl-5 '-deoxy-5 '-iodo-adenosine.

EXAMPLE 4 5 -deoxy-5 JodaB-D-ribofuranosyl purines Repeating the procedure of Example 3 but replacing N-benzoyl-2' ,3-O-isopropylidene-adenosine with N -benzoyl-2',3'O-isopropylidene-2- fluoroadenosine, N -benzoyl-2',3'-O-isopropylidene-Z-azaadenosine, N -benzoyl-2'-3'-O-isopropylidene-7- deazaadenosine, N -benzoyl-2'-3'-O-isopropylidene-8-azaadenosine, N-benzoyl-2'-3'-O-isopropylidene-8-aza-9- deazaadenosine N -benzoyl-2'-3'-O-isopropylidene-7-deaza-7- cyanoadenosine, N -benzoyl- N methyl-Z ',3 '-O- isopropylideneadenosine, N-dimethyl-2 ,3 -O-isopropylidene-adenosine, N -acetyl-2 ',3 -O-isopropylidene-guanosine, N -acetyl-2',3'-O-isopr0pylidene-8-azaguanosine, N -acetyl-2',3'-O-isopropylidene-7-deazaguanosine, N-acetyl-2,3'-O-isopropylidene-isoguanosine, 2',3'-O-isopropylidene-inosine, and 2,3'-O-isopropylidene-xanthosine yields the corresponding N -benzoyl-5 '-deoxy-5 '-iodo-2-fluoroadenosine, N -benzoyl-S '-deoxy-5 '-iodo-2-azaadenosine, N-benzoyl- 5' -deoxy-5 '-iodo-7-deazaadenosine, N-benzoyl-5 -deoxy-S '-iod0-8-azaadenosine,' N-benzoyl-5 -deoxy-5 '-iodo-8-aza-9- deazaadenosine, N -benzoyl-5 '-deoxy-5 -iodo-7-deaza-7- cyanoadenosine, N-benzoyl-N-methyl-5 -deoxy-5 -iodo-adenosine, N-dimethyl-5 '-deoxy-5 -iodo-adenosine, N -acetyl-5 '-deoxy-5 -iodo-guanosine, N -acetyl-5 -deoxy-5 '-iodo-8-azaquanosine, N' -acetyl-5 -deoxy-5 '-iodo-7-deazaguanosine, N -acetyl-5 -de0xy-5 -iodo-isoguanosine, 5 '-deoxy-5 '-iodo-inosine, and S '-deoxy-5 '-iodo-xanthosine.

EXAMPLE 5 l 2, 3-O-carbonyl-5 -deoxy-B-D-erythro-pent-4- enofuranosyl )-uracil 5'-deoxy-5-iodouridine (l mmole) is dissolved in 10 ml. of dry pyridine containing l,S-diazabicyclo [4.3.0]- non-S-ene (2 mmoles). The reaction mixture is held at 40C. for 20 hours in the dark and then cooled to C. To this reaction mixture, 1.6 ml. of a 12.5 percent solution of phosgene in benzene is added under anhydrous conditions and vigorous stirring and the temperature is then allowed to warm to 20C. One hour after the addition of phosgene the mixture is evaporated to dryness and the residue is partitioned between ethyl acetate and water. This ethyl acetate layer is dried over magnesium sulfate, filtered, decolorized with charcoal, filtered again and finally evaporated to dryness. The resulting residue is crystallized from ethyl acetate to yield l-( 2.3,-O-carbonyl-S-deoxy-fiD-erythropent-4-enofuran0syl )-uracil.

l7 l8 Nacetyl-2 ',3 '-O-carbonyl-5 -deoxy-5 '-i0do-4- EXAMPLE 12 methoxwyuldme I I l-(S-deoxy-S-ido4-methoxy-B-D- N"-acetyl-2 ,3 -O-carbonyl- -deoxy-5 -|odo-4 ribofuranosynpyrimidines and methOXYS'flUOmCyIdme I 9-( 5-deoxy-5-iodo-4-methoxy-,B-D-ribofuranosyl) N-acetyl-2,3'-O-carbonyl-5-deoxy-5'-iodo-7'- 5 purines Repeating the procedure of Example I l but replacing 2 ',3 -O-carbonyl-5 '-deoxy-5 '-iodo-4 '-methoxy- 4'-methoxy-Z-fluoroadenosine,

aza-S-methyl uridine,

5 '-de0xy-5 -iodo-4 '-methoxy-uridine 4'-methoxy-8-azaadenosine,

N,N-dibenzoyl-2 ',3 '-O-carbonyl-5 '-deoxy-5 '-iod0 4 -methoxy-8-aza-9-deazaadenosine,

N,N"-dibenzoy1-2'-3 -O-carbonyl-5 '-de0xy-5 -iodo- 4'-methoxy-7-deaza-7-cyanoadenosine,

N -benZOyI-N -methyI-Z ',3 -O-carbonyl-5 -deoxy-5 i0do-4 '-methoxy-adenosine,

N -dimethyl-2',3-O-carbonyl-5-deoxy-5'-iodo-4'- methoxy-adenosine,

N -acetyl-2 ',3 '-O-carbonyl-5 '-deoxy-5 '-i0d0-4 methoxy-guanosine,

N -acetyl-2',3 '-O-carbonyl5 '-deoxy-5 -iodo-4'- methoxy-8-azaguanosine,

N -acetyl-2 ',3 -O-carbonyl-5 -deoxy-5 '-iodo-4'- methoxy-I-deazaguanosine,

2,3 '-O-carbonyl-5 '-deoxy-5'-iodo-4-methoxyuridine (l mmole) is dissolved in 25 ml. of methanol containing sodium methoxide (2 mmoles). After 18 hours at 20C., the reaction mixture is neutralized by the addition of an ion exchange resin (Amberlite lRC 5O COOH"). The reaction mixture is then filtered, the resin is thoroughly washed with methanol, and the combined filtrate and washings are evaporated to dryness The residue is purified by chromatography over silica gel to separate the main fraction consisting of 5'- deoxy-S-iodo-4'-methoxy-uridine from trace amounts of l-( S-deoxy-S-iodo-4-methoxy-a-L-lyxofranosyl uracil.

N "-acetyl-2 ,3 '-O-carbonyl-5 '-deoxy-5 '-iodo-4'- methoxy-isoguanosine,

2 ,3 '-O-carbonyl-5 -deoxy-5 -iodo-4'-methoxyinosine, and

2',3'-0-carbonyl-5'-deoxy-5-iodo-4'-methoxyxanthosine yields the corresponding 5 -deoxy-5 '-iodo-4'-methoxy-5-fluorouridine,

5'-deoxy-5'-iodo-4'-methoxy-5-butyluridine,

5 -deoxy-5 '-iodo-4'-methoxy-5- trifluoromethyluridine,

5-deoxy-5'-iodo-4'-methoxy-5-nitrouridine.

5-deoxy-S'-iodo-4'-methoxy-5-methylaminouridine,

5'-deoxy-5'-iodo-4-methoxy-5- dimethylaminouridine,

5'-deoxy-5'-iodo-4-methoxy-6-azauridine,

5-deoxy-5'-iodo-4'-methoxy-6-aza-5-methyluridine,

5'-deoxy-5'-iodo-4-methoxy-cytidine,

5 '-deoxy-5 '-iodo-4'-methoxy-5-butylcytidine,

5 '-deoxy-5 '-iodo-4'-methoxy-S-trifluoromethylcytidine,

5'-deoxy-5'-iodo-4'-methoxy-S-nitrocytidine,

5'-deoxy-5'-iodo-4'-methoxy-5- methylaminocytidine,

5-deoxy-5'-iodo-4'-methoxy-5- dimethylaminocytidine.

5'-deoxy-5'-iodo-4-meth0xy-6-a.zacytidine,

5'-deoxy-5'-iodo-4-methoxy-6-aza-5- methylcytidine,

5 '-deoxy-5 -iodo-4-methoxy-adenosine,

5 -deoxy-S -iodo-4'-methoxy-2-fluoroadenosine,

5 '-deoxy-5 -iodo-4' -methoxy-2-azaadenosine,

5 '-deoxy-5 -iodo-4' -methoxy-7-deazaadenosine,

5-deoxy-5'-iodo-4'-methoxy-8-azaadenosine,

5-deoxy-5'-iodo-4'-methoxy-8-aza-9- deazaadenosine,

S'-deoxy-5'-iodo-4'-methoxy-7-deaza-7- cyanoadenosine.

N -methyI-S-deoxy-5-iodo-4-methoxy-adenosine,

N"'-dimethyl-5-deoxy-5 '-iodo-4-methoxyadenosine,

5 '-deoxy-5' -ido-4-methoxy-guanosine '-deoxy-5 -iodo-4-methoxy-8-azaguanosine,

5 '-deoxy-5 -iodo-4'-methoxy-7-deazaguanosine,

5 '-deoxy-5 -iodo-4-methoxy-isoguanosine,

5 '-deoxy-5'-iodo-4-methoxy-inosine, and

5 'deoxy-5 -iodo-4'-methoxy-xanthosine.

EXAMPLE 13 l-( S-deoxy-S-iOdo-4-methoxy-a-Llyxofuranosyl uracil 5'-deoxy-5-iodo-4'-meth0xy-uridine l mmole) is dissolved in 50 m]. of 0. l N hydrochloric acid in methanol and the equilibration is followed by thin layer chromatography. After 24 hours, most of the starting material has been converted to the a-L-lyxo isomer. The reaction mixture is then neutralized with concentrated ammonium hydroxide and the lyxo isomer is purified by chromatography over silica gel to yield l-(S-deoxy- 5-iodo-4-methoxy-a-L-lyxofuranosyl )-uracil.

Repeating the above procedure with compounds obtained in Examples 1 1 and 12 yields the corresponding a-L-lyxo isomers.

EXAMPLE l4 3'-Obenzoyl-2'-deoxy-uridine 2-deoxyuridine l0 mmoles) is dissolved in l0 ml. of dry pyridine and monomethoxy trityl chloride l l mmoles) is added. After 20 hours at 20C., benzoyl chloride (11 mmoles) is added and the reaction mixture is held at 20C. for another 20 hrs. The solvents are then removed by evaporation and the residue is dissolved in 500 ml. of a 20 percent aqueous acetic acid solution. After 5 hours at 20C. the reaction mixture is evaporated to dryness at 30C. under high vacuum. The residue is leached with hot benzene and ether and is then purified by chromatography over silica gel. The main nucleoside fraction is concentrated to a syrup, thoroughly dried by repeated evaporation from dimethylformarnide and crystallized from ethanol to yield 3-Obenzoyl-2'-deoxyuridine.

EXAMPLE I 5 3 '-O-benzoyl-2-5 '-dideoxy-5 '-iodo-uridine The 3-O-benzoyl-2'-deoxyuridine prepared in Example M is dissolved in 10 ml. of dimethylformamide and methyltriphenoxyphosphoniurn iodide l .2 equivalent) is added. After 5 hours at 20C the reaction mixture is evaporated to dryness. The resulting residue is partitioned between ethyl acetate and a l0 percent aqueous sodium thiosulfate solution. The organic layer is washed with water, dried with magnesium sulfate, filtered and evaporated to dryness. The resulting residue is purified by chromatography over silica gel and the main nucleoside fraction evaporated to dryness to yield 3-O-benzoyl-2'-5'-dideoxy-5-iodouridine.

EXAMPLE 16 l( 3-O-benzoyl-2-5-dideoxy-B-D-glycero-pent-4- enofuranosyl )-uracil The 3-O-benzoyl-2',5'-dideoxy-5'-iodo-uridine prepared in Example 15 is dissolved in dry pyridine 10 ml. mmole of nucleoside) and silver fluoride (2.5 equivalents) is added. The suspension is stirred vigorously for 4 days in the dark at 20C. and then filtered. The filtrate is evaporated to a thin syrup and then partitioned between ethyl acetate and water. The two-phase system is filtered through Celite and the organic layer separated, dried over magnesium sulfate, filtered and evaporated to dryness. The resulting residue is purified over silica gel to yield l-(3-O-benzoyl-2 ,5 -dideoxy-B-D- glycer0-pent-4-enofuranosyl) uracil.

EXAMPLE l7 1-(3 -O-benzoyl-2 ,5 -dideoxy-B-D-glycero-pent-4-enofuranosyl pyrimidines Repeating the procedures of Examples 14-16 in sequence but replacing 2'-deoxyuridine in Example 14 with 2 '-deoxy-5 -fluorouridine,

2'-deoxy-5-butyluridine,

2'-deoxy-5-trifluoromethyluridine,

2-deoxy-S- nitrouridine,

2'-deoxy-S-methylaminouridine, 2'-deoxy-S-dimethylaminouridine, 2'-deoxy-6-azauridine, 2-deoxy-6aza-5methyluridine,

N-benzoyl-2'-deoxy-cytidine,

2 1 N-benzoyl-2'-deoxy-5-fluoroeytidine, N-benzoyl-2 '-deoxy-5-butylcytidine N-benzoyl-2 '-deoxy-5-trifluoromethylcytidine, N -benzoyl-2'-deoxy-5-nitrocytidine, N-benzoyl-2 '-deoxy-S-methylaminocytidine, N-benzoyl-2'-deoxy-S-dimethylaminocytidine. N -benzoyl-2'-deoxy-6-azacytidine,

N"-benzoyl-2 '-deoxy-6-aza-5-methylcytidine,

yields the corresponding l-( 3-O-benzoyl-2,5-dideoxy-B-D-glycero-pent-4- enofuranosyl )--fluorouracil,

l-( 3-O-benzoyl-2 ,S-dideoxy-B- D-glycero-pent-4- enofuranosyl )-5 -butyluracil,

l-( 3-O-benzoyl-2,5-dideoxy-fl-D-glycero-pent-4- enofuranosyl )-5-trifluoromethyluracil,

l-( 3-O-benzoyl-2,5-dideoxy-B-D-glycero-pent-4- enofuranosyl )-5-nitrouracil,

l-( 3-O-bcnzoyl-2,5-dideoxy-B-D-glycero-pent-4- enofuranosyl )-5 -methylaminouracil,

l-( 3-O-benzoyl-2,5-dideoxy-B-D-glycero-pent-4- enofuranosyl )-5-dimethylaminouracil,

l-( 3-O-benzoyl-Z.S-didcoxy-B-D-glycero-pent-4- enofuranosyl )-6-azauracil,

l-( 3-O-benzoyl-2,5-dideoxy-B-D-glycero-pent-4- enofuranosyl )-6-aza- S-methyluracil,

N-benzoyll 3-O-benzoyl-2,S-dideoxy-B-D- glyceropent-4-enofuranosyl )-cytosine,

N*-benzoyll-( 3-O-benzoyl-2,S-dideoxy-fi-D- glyceropent-4-enofuranosyl )-5-fluorocytosine,

N-benzoyll 3-O-bcnzoyl-2,S-dideoxy-B-D- glyceropent-4-enofuranosyl )-5-butylcytosine,

N -benzoyll 3-O-benzoyl-2,5-dideoxy-/3-D- glyceropent-4-enofuranosyl )-5-trifluoromethylcytosine,

N*-benzoyll 3-O-bcnzoyl-2,5-dideoxy-B-D- glyceropent-4-enofuranosyl )-5-nitrocytosine,

N-benzoyll-( 3-O-benzoyl-2,5-dideoxy-B-D- glyceropent-4-enofuran0syl )-5- methylaminocytosine,

N-benzoy!- l-( 3-O-benzoyl-2,S-dideoxy-B-D- glyceropcnt-4-enofuranosyl )-5- dimethylaminocytosine,

N -benzoyll 3-O-benzoyl-2,5dide0xy-B-D- glyceropent-4-enofuranosyl )-6-azacytosine, and

N-benzoyll 3-O-benzoyl-2,5-dideoxy-B-D- glyceropent-4-enofuranosyl )-6-aza-S- methylcytosine.

EXAMPLE l8 N-benzoyll B-D-arabinofuranosyl )-cytosine l-(B-D-arabinofuranosyl)-cytosine l mmole) is suspended in 25 ml. of dry ethanol and 250 mg. of benzoic anhydride is added. The reaction mixture is stirred at reflux and 500 mg. of benzoic anhydride is added at 1 hour intervals until 25 g. has been added. After the final addition the solution is refluxed for 1 hour, cooled and evaporated under vacuum. Trituration of the resulting syrupy residue with ether affords crystals. The suspension is filtered and the solid triturated three times with 50 ml. portions of warm etherr The residue is evaporated to dryness to yield N*-benzoyl-l-(B-D- arabinofuranosyl )-cytosine.

EXAMPLE l9 N -benzoyll -(B-D-arabinofuranosyl )-cytosines Repeating the procedure of Example 23 but replacing l-( BD-arabinofuranosyl )-cytosine with l-(B-D-arabinofuranosyl )-5-fluorocytosine,

l(B- D-arabinofuranosyl )-5-butylcytosine,

|-( ,B- D-arabinofuranosyl )-5-trifl uoromethylcytosine,

l-( B-D-arabinofuranosyl )-S-nitrocytosine,

l-( B-D-arabinofuranosyl )-5-methylaminocytosine l-( B- D-arabinofuranosyl )-5-dimethylaminocytosine,

l'-( fl-D-arabinofuranosyl )-6-azacytosine and l-( B-D-arabinofuranosyl )-6-a.za-5-methylcytosine.

yields the corresponding N-benzoyll B-D-arabinofuranosyl )-5- fluorocytosine,

N"-benzoyll B-D-arabinofuranosyl )-5- butylcytosine,

N-benzoyll B-D-arabinofuranosyl )-5 -trifluoromethylcytosine,

N*-benzoyl- 1-( ,B-D-arabinofuranosyl )-5- nitrocytosine,

N benzoyll B-D-arabinofuranosyl )-5- methylaminocytosine,

N -benzoyll B-D-arabinofuranosyl )-5- dimethylaminoeytosine,

N -benzoyll B-D-arabinofuranosyl )-6-azacytosine.

and

N -benzoyll B-D-arabinofu ranosyl )-6-aza-5 methylcytosine.

EXAMPLE 20 N N-dibenzoyl-9( 2,3-cli-O-benzoyl-B- D- arabinofuranosyl )-adenine Q-(B-D-arabinofuranosyl)-adeninc l0 mmoles) is dissolved in 200 ml. of dry pyridine and monomethoxy trityl chloride l l mmoles) is added. After 20 hours at 20 C., benzoyl chloride (80 mmoles) is added and the reaction is held at 20C for another 20 hours. The excess reagent is destroyed by the addition of water and the reaction mixture is evaporated to dryness under vacuum. The residue is partitioned between chloroform and water and the organic layer is evaporated to dryness. The resulting residue is then dissolved in 500 ml. of a mixture of acetic acid and water (8:2). After 5 hours at 20C the solvents are removed under reduced pressure and low temperature (i.e. 2030C). The residue is purified by chromatography over silica gel and the major nucleoside fraction is evaporated to dryness to yield N ,N-dibenzoyl-9( 2,3-di-O-benzoyl-B- D-arabinofuranosyl )-adenine.

EXAMPLE 2l N,N-dibenzoyl-9-(2,3-di-O-benzoyI-S-deoxy-S- iodo-B-D-arabinofuranosyl )-adenine.

The N ,N-dibenzoyl-9-( 2 ,3-di-O-benzoyl-BPD- arabinofuranosyl)-adenine prepared in Example 20 is dissolved in 10 ml. of dry methylene chloride and the solution is cooled to C. Methyltriphenoxyphosphonium iodide (1.5 equivalents) is then added in a dry nitrogen atmosphere and the reaction mixture is allowed to warm to 20C. Two hours after the addition of methyltriphenoxyphosphonium iodide, methanol l0 equivalents) is added to decompose excess reagent. The solvents are evaporated under vacuum at 30C and the residue is partitioned between chloroform and wa- N N"-dibenzoyl-9-( 2, S-di-O-benzoyl-S-dexoy-S- -4-methoxy-B-D-arabinofuranosyl )-2-azaadcnine,

D-arabinofuranosyl)-cytosine prepared in Example 31 is dissolved in 20 ml. of a mixture of methanol and concentrated ammounium hydroxide l: l The hydrolysis is pursued for 20 hours at 40C. The reaction mixture NI N6 dibenZOy| 9 (z,3 di o benzoyl 5 dcOxy 5 is then evaporated to dryness and the residue purified -4-methoxy-B-D-arabinofuranosyl )-7- deazaadenine, N ,N, dibenzoyl-9-(2,3-di-O-benzoyl-5-deoxy-5- -4-methoxy-B-D-arabinofuranosyl )-8- dcazaadcnine, N ,N, dibenzoy|-9-( 2,3-di-O-benzoyl-5-deoxy-5- -4-methoxy-,B-D-arabinofuranosyl )-8-aza-9- deazaadenine, N ',N-dibenzoyl-9-( 2, B-di-O-benzoyl-S-deoxy-S- EXAMPLE 3] N ben2oyl-1-(2,3,5-tri-Obenzoyl-4-methoxy-B-D- arabinofuranosyl )-cytosine Nbenzoyll 2,3-diO-benzoyl-5-deoxy-5-iodo-4- methoxy-B-D-arabinofuranosyl)-cytosine mmole) is dissolved in ml. of hexamethylphosphorotriamide and lithium benzoate (6 mmole) is added. After 24 hours at 105C the solvent is evaporated at 90-lOOC'. under vacuum and the residue is taken up in ml. of ethyl acetate. The insoluble precipitate is removed by filtration. the filtrate is evaporated to dryness and the residue purified by preparative thin layer chromatography over silica gel. The main UV band is eluted from the silica gel with methanol. Evaporation of the solvent yields N benzoyl-l-(2,3,4-tri-O-benzoyI-4-methoXy-B- D-arabinofuranosylJ-cytosine.

EXAMPLE 32 l-( 4-methoxy-B-D-arabinofuranosyl )-cyt0sine The Nbenzoyl- 2,3,5-tri-O-benzoyl-4 -methoxy-B- by preparative thin layer chromatography over silica gel. Each UV band is eluted from the silica gel with methanol, evaporated to dryness and analyzed by UV and NMR. The band corresponding to l-(4-methoxy-[3- D-arabinofuranosyl)-cytosine is then further purified over silica gel to give the analytically pure nucleoside.

' EXAMPLE 33 l-( 4-methoxy-[3-D-ribofuranosyl) pyrimidines,

9-(4-methoxy-B-D-ribofuranosyl) purines, l-( 2-deoxy-4-methoxy-B-D-erythro-pentofuranosyl) 20 pyrimidines,

l-( 4-methoxy-B-D-arabinofuranosyl )pyrimidincs, and 9-( 4-methoxy-B-D-arabinofuranosyl )purines Repeating the procedures of Examples 3] and 32 but 25 replacing N*-benzoyll 2,3-di-O-benzoyl-5-dcoxy-5- iodo-4-methoxy-B-D-arabinofuranosyl)-cytosine in Example 3l with l\l ,O ,O" -tribenzoyl-5 '-deoxy-5 '-iodo-4'- methoxyuridine, 30 N 0 ,O -tribenzoyl-5 '-deoxy-5 '-iodo-4 methoxy-S-fluorouridine, N",O I ,O I trihenzoyl-5 '-deoXy-5 '-iodo-4 methoxy-S-butyluridine,

methoxy5nitrouridine,

N,O ,O" tribenzoyl-5"deoxy-5'-iodo-4'- methoxy-S-methylaminouridine,

,O' -tribenzoyl-5'-deoxy-S-iodo-4'- methoxy-S-dimethylaminouridine,

N10 ,O'" -tribenzoyl-5'-deoxy-5'-iodo-4'- methoxy-o-azauridine,

methoxy-o-aza-S-methyluridine,

methoxy-S-butylcytidine,

N,O ,O' -tribenzoyl-5'-deoxy-5'iodo-4' methoxy-S-nitrocytidine,

N,O ,O" tribenzoyl-5-deoxy-S -iodo-4- methoxy-S-methylaminocytidine,

N,O ,0 -tribenzoyl-5 '-deoxy-5 '-iodo-4'- methoxy-idimethylaminocytidine,

N ,O ,O'" -tribenzoyl-5'-deoxy-5'-iodo-4'- methoxy-6-azacytidine,

N,O ,O -tribenzoyl-5-deoxy-5'-iodo-4- methoxy-6-aza-5-methylcytidine,

NKNiO ,0" -tetrabenzoyl-5'-deoxy-5'-iodo-4'- methoxy-adenosine, 

1. A COMPOUND SELECTED FROM THE GROUP OF COMPOUNDS REPRESENTED BY THE FORMULA:
 2. A compound of claim 1 wherein R is methyl.
 3. A compound of claim 2 wherein B is a pyrimidine base.
 4. The compound of claim 3 which is 4''-methoxy-uridine.
 5. The compound of claim 3 which is 4''-methoxy-cytidine.
 6. The compound of claim 3 wherein B is 5-fluorouracil-1-yl; 1-(2-deoxy-4-methoxy- Beta -D-erythro-pentofuranosyl)-5-fluorouracil.
 7. The compound of claim 3 wherein B is cytosin-1-yl; 1-(4-methoxy- Beta -D-arabinofuranosyl) cytosine.
 8. The compound of claim 3 wherein B is a hydrolyzable benzoyl derivative of a pyrimidine base and R4, R5 and R6 are benzoyl groups.
 9. The compound of claim 8 which is N4-benzoyl-1-(2,3,5-tri-O-benzoyl-4-methoxy)cytidine.
 10. The compound of claim 8 which is N4-benzoyl-1-(2,3,5-tri-O-benzoyl-4-methoxy- Beta -D-arabinofuranosyl)cytosine.
 11. The compound of claim 8 which is N4-benzoyl-1-(2,3,5-tri-O-benzoyl-4-methoxy- Beta -D-arabinofuranosyl)-5-fluorocytosine.
 12. A compound of claim 2 wherein B is a purine base.
 13. The compound of claim 12 wherein B is 8-aza-9-deazaadmin-9-yl; 4''-methoxy-8-aza-9-deazaadenosine.
 14. The compound of claim 12 wherein B is 2-fluoroadenin-9-yl; 4''-methoxy-2-fluoroadenosine.
 15. The compound of claim 12 which is 4''-methoxy-adenosine.
 16. The compound of claim 12 wherein B is N6-dimethyladenin-9-yl; N6-dimethyl-4''-methoxy-adenosine.
 17. The compound of claim 12 wherein B is adenin-9-yl; 9-(4-methoxy- Beta -D-arabinofuranosyl) adenine.
 18. The compound of claim 12 in which B is a hydrolyzable benzoyl derivative of a purine base and R4, R5 and R6 are benzoyl groups.
 19. The compound of claim 10 which is N6-benzoyl-9-(2,3,5-tri-O-benzoyl-4-methoxy- Beta -D-Arabinofuranosyl)adenine.
 20. A compound selected from the group represented by the formula 